Surgical catheter



Sept. 7, 1965 w. R. KOEHN SURGICAL CATHETER 2 Sheets-Sheet 1 OriginalFiled Jan. 15, 1961 FIG. 3

INVENTOR.

Sept. 7, 1965 w. R. KOEHN SURGICAL CATHETER 2 sheets sheet 2 OriginalFiled Jan. 13, 1961 /2 FIG. /0

BY 5 4a,,

United States Patent 3,264,634 SURGIQAL CATHETER Wilbur R. Koehn,Sherwood Drive, Sands Point, N.Y. Original application Jan. 13, 1961,Ser. No. 82,534. Di-

vided and this application Feb. '5, 1964, Ser. No.

Claims. (Cl. 128214) This application is a continuation-in-part of priorap lication Serial No. 690,709, filed October 17, 1957, now Patent No.3,030,953, issued April 24, 1962, and a division of prior applicationSerial No. 82,534, filed January 13, 1961, now abandoned.

The present invention relates to surgical catheters and moreparticularly to a method of fabricating a catheter directly on a needleand the resulting combined needle and catheter which facilitates theinsertion of the catheter into a body cavity of a patient.

It is the usual practice in blood transfusions intravenous feedings, orwhen fluids are to be withdrawn from the human body to attach a hollowneedle to an end of a tube and insert the needle into a vein or otherbody cavity. The fluid then flows from a source through the tube andhollow needle into the body when fluids are to be delivered thereto, orfrom the body through the needle and tube when fluids are to bewithdrawn. Repeated punctures of veins with metal needles tend to causeVenus thromboses and subcutaneous hematomas. To avoid this result themetal needle is sometimes left in the body. However, the metal needle isapt to cause an infection and the part of the body where the needle isinserted must be immobilized with considerable discomfort to thepatient. This is especially true when the needle is inserted into a veinas, for example, in the arm where relative movement might cause apuncturing of the vein and produce additonal trauma. To prevent suchrelative movement the arm is usually strapped in a fixed position.

Obviously, it is desirable to insert the end of a relatively soft,flexible catheter into the body cavity, in place of a metal needle, toeliminate the necessity of immobilizing the arm or other portion of thebody of the patient and the resulting discomfort.

One of the objects of the present invention is to provide an improvedmethod of fabricating a catheter directly on the needle used to insertthe end of the catheter in a body cavity.

Another object is provide an improved needle and catheter in aself-contained sterile unit which facilitates the insertion of the endof the catheter into a body cavity and the removal of the needletherefrom.

Still another object is to provide an improved catheter and needle unitwhich is of relatively simple and compact construction, adapted foreconomical manufacture as a disposable unit and one which is reliable inoperation for inserting the end of a plastic catheter into a bodycavity.

These and other objects will become more apparent from the followingdescription and drawings in which like reference characters denote likeparts throughout several views. It is to be expressly understood,however, that the drawings are for the purpose of illustration only andare not a definition of the limits of the invention, reference being hadfor this purpose to the appended claims.

In the drawings:

FIGURE 1 is a side elevational view of a combined catheter and needleunit made in accordance with the method of the present invention;

FIGURE la is an enlarged View of the beveled end of the needle andcatheter to show the rounded contour of the end of the catheter;

FIGURE 2 is a view illustrating one method of dipping a needle in aliquid containing a plastic at an angle to the surface of the liquid tocoat the needle with plastic from adjacent its pointed end;

FIGURE 3 is a view similar to FIGURE 2 showing an alternate method ofmoving the needle in a bath of the liquid to produce a plastic coatingthereon with an end conforming generally with the beveled end of theneedle.

FIGURE 4 shows the coated needle hung vertically from its pointed end tocause the liquid plastic to fiow by gravity and produce a coating havinga thin rounded edge adjacent the pointed end of the needle and ofprogressively increasing thickness from its pointed end;

FIGURE 5 is a view similar to FIGURE 4 showing the coating of plasticcut around the periphery of the handle or hub of the needle to form thecatheter and a cap applied over the needle and catheter;

FIGURE 6 is a side elevational view similar to FIG- URE 5 showing thecap removed and the cut end of the plastic coating stripped from thehandle to prepare it for use;

FIGURE 7 illustrates the manner of inserting the end of the needle andcatheter assembly into a body cavity;

FIGURE 8 is a view similar to FIGURE 7 showing the manner in which theneedle is withdrawn from the catheter;

FIGURE 9 shows the tapered fitting at the end of the catheter adaptedfor connection to a fitting on a tube for supplying or removing fluidsto or from the body;

FIGURE 10 is a view similar to FIGURE 9 illustrating a removable plugwhich may be inserted in the catheter to stop the flow of fluidtherethrough; and

FIGURE 11 is an enlarged fragmentary elevational view of the forward endof the surgical catheter with certain parts broken away, removed andsectioned.

In accordance with the method of the present invention, a catheter tube2 of a plastic resin is fabricated directly on the needle 3 with whichit is used whereby the needle constitutes a mandrel to form the insideof the catheter to the desired shape. Surprisingly, such a plasticcatheter 2 formed directly on the needle 3 can be easily and quicklyremoved, after the pointed end of the needle and adjacent end of thecatheter have been inserted into the body cavity, by merely withdrawingthe needle with one hand while the catheter is held by the other hand.

In accordance with the present invention, a hollow needle 3 is providedhaving a beveled cutting edge at one end 4 and a handle or hub 5 at theopposite end. Needle 3 must have a smooth peripheral surface which may'be of the same diameter throughout its length, or tapered outwardlyfrom the pointed end 3, but must not taper inwardly or have any recessedareas rearwardly of the pointed end. The hollow needle 3 may be formedin a conventional way by drawing a seamless tube of, for example,stainless steel through a forming die and the end 4 pointed by grindingit on a bias to provide a sharp cutting edge extending rearwardly aroundthe entire periphery of the end of the needle. The handle 5 is alsohollow and surrounds the shank of the needle adjacent its rearward end.Thus, when the pointed end 3 of the needle is inserted into a vein,blood will flow through the needle and hollow handle. The handle 5 maybe made of any suitable chemically inert material which will withstandthe temperature required to cure the plastic catheter. For example, thehandle may be composed of Teflon or nylon or any other chemically inertplastic or may be composed of metal. As shown in the drawings, theexterior of the handle 5 has a conical tapered portion 6 adjacent theneedle 3 and a cylindrical portion 7 projecting rearwardly from theconical portion 6. The interior of the outer end of handle 5 has aconical tapered portion 8 of a shape corresponding to the shape of theportion 6.

The tapered portions 6 and S constitute standard Luer fittings and thefitting 8 adapts the handle 7 to be mounted on a conventional syringefor holding the needle and catheter.

The catheter 2 may be made from any suitable chemically inert andnon-toxic plastic resin which is stiff enough to follow the pointed end4 of the needle 3 through human tissue and flexible enough to conform tothe contour of body cavities into which it is inserted. For example, thecatheter 2 may be made from plastisols or organisols of vinyl resin orpolyethylene resin in solution or suspension. As used herein the termplastisols comprise particulate suspensions of the plastic resin in aliquid plasticizer; and the term organisols comprise plastisolscontaining a thinner. For example, if the catheter 2 is to be made ofvinyl resin, the resin in a fine, granular form is dispersed in asuitable plasticizer, such as di-octyl phthalate, which may be furtherdiluted to a desired consistency by the addition of a suitable thinner,such as naptha or other volatile liquid solvent for the plasticizerwhich will not produce solvation of the vinyl particles. When thecatheter is to be made of polyethylene, the resin may be dissolved inany suitable hot solvent, such as, for example, one of a group includingxylene, toluene or amyl acetate at a temperature above 140 F. Instead ofa hot solution, the granular polyethylene resin may be dispersed in acold suspension of, for example, Xylene and the needle 3 heated abovethe temperature of 140 F. The heated needle then dissolves the resingranules and produces a thin uniform coating on the needle andsimultaneously evaporates the solvent to leave a continuous film of thepure plastic. While'two examples of vinyl and polyethylene resins havebeen given, it will be understood that dispersions, suspensions orsolutions of any other suitable plastic resin of a consistency fordipping may be used.

The plastisol, organisol, suspension or solution of the plastic materialis placed in a tank 10, as shown in FIG- URES 2 and 3, and maintained atthe proper temperature and/ or consistency to produce a liquid coatingof the desired thickness when the needle 3 is dipped therein. Whendipping, the entire needle 3 is immersed in the solution to a depth sothat all except the pointed end 4 is coated. When the needle 3 is coatedin the manner illustrated in FIGURE 2, the needle is held at an angle sothat the plane of the flat beveled end 4 is parallel to the surface ofthe plastic solution in the tank 10. This may be accomplished bymounting the needle or needles 3 to be coated on a Wire or wires havingan angular end extending into the hollow ends of the needles to supportthem at the proper angle. The needle or needles 3 are immersed to adepth at which the level of the liquid containing the plastic materialis closely adjacent and parallel to the flat pointed end 4, as shown inFIGURE 2. After dipping, the needles 3 are withdrawn from the tank witha coating of the plastic thereon.

In accordance with a modified method of coating the needle 3 as shown inFIGURE 3, the needle is immersed vertically so that only the pointed end4 projects above the surface of the solution in the tank 10 and theneedle moved bodily in a direction at right angles to the point of theneedle. The horizontal movement of the needle through the viscousmaterial causes it to pile up in front of the needle in a wave to coatthe needle in a plane roughly parallel .to its beveled end 4.

The needle 3 coated with a film of the liquid plastic is then hung fromits pointed end 4. In the case of organisols the coating may be heatedat a low temperature to drive off the thinning solvent. During thehanging operation the coating tends to run down the sides of the needleand handle 5 by gravity and produces a layer of gradually increasingthickness from adjacent the pointed end of the needle 3 to the lower endof the handle 5. Following the hanging and dripping operations theentire assembly, as illustrated in FIGURE 4, is subjected to atemperatpre which will cure the liquid plastic coating and form a stableplastic layer. For example, when the needle is coated with a plastisolor organisol of a vinyl resin, it is heated to 350 F. for a period ofapproximately four minutes. In addition to curing the plastic, the 350F. temperature sterilizes the needle and plastic coating thereon. Whenthe needle 3 and handle 5 are preheated and dipped in a cold suspensionof polyethylene, for example, the heated needle causes the particles ofplastic adjacent the needle to go into a solution which gel at thesurface of the needle. The further heating of the gelled solution on theneedle then produces a complete solvation of the polyethylene resinparticles which are fused in a solid body of the clear plastic.Furthermore, the heat drives out the solvent in the coating.

After the needle 3 has been dipped to form the coating and then heatedto cure the plastic, the enclosing coating is cut on a circular linearound the periphery of the handle 5, to form the catheter 2. A cap 9 isthen applied over the needle 3 and catheter 2 thereon with the endextending beyond the circular cut and engaging the plastic sleeve 11beyond the cut to provide a sealed joint. Thus, cap 9 provides ahermetically sealed sterile unit.

Preferably, the needle 3 is twice dipped in liquids containing plasticsand at diflierent consistencies to form a catheter 2 having a relativelythin and flexible tube and a thicker and stifler conical end 12. Forpurposes of description, let it be assumed that the catheter 2 is to bemade of a vinyl resin. The entire needle 3, except the pointed end, isfirst dipped into an organisol of the vinyl resin comprising about 50%plasticizer and suflicient thinner to produce a coating, when cured,having a thickness of from .005 inch to .008 inch at its end adjacentthe pointed end of the needle and a thickness of from .010 inch to .013inch at the conical section 6. The vinyl coating is then cured at atemperature of 350 F. for approximately four minutes. The handle end 5of the needle 3, only, is then redipped in a plastisol of the vinylresin comprising 35% plasticizer, but only to where the needle andhandle join each other. The more viscous plastisol then deposits athicker layer of the plastic on the tapered portion 6 of the handle 5.The second coating of vinyl resin permeates the underlying coating andthe product is again cured at a temperature of 350 F. for another periodof approximately four minutes. The resulting catheter has a relativelysoft, flexible tube extending from adjacent the pointed end of theneedle to one handle 5 and a harder and thicker conical end portion 12.When other plastic resins are used, the liquids containing the plasticsare so formed as to produce a thin coating on the needle shank and athicker and stiffer coating of the conical portion 6 of the handle 5.

The pointed end of the combined catheter 2 and needle 3 then is insertedthrough the tissue of the human body into a cavity, such as a vein, asillustrated diagrammatically by the reference character V. Due to theclose fit of the forward end of the catheter 2 with the periphery of theneedle 3 on which it was formed and the thinness of the end of thecatheter 2, due to flow of the plastisol along the needle, the end ofthe catheter follows the pointed end of the needle into the body cavity.When the ends of the needle and catheter have entered a body cavity,such as a vein V blood will flow through the hollow needle 3 and handle5 to indicate that the end of the catheter is properly position, asillustrated in FIG- URE 7. The rearward end of the catheter 2 is thenheld between the forefinger and thumb of one hand while the handle 5 ofthe needle 3 is held between the forefinger and thumb of the other handand withdrawn relative to the catheter 2, as illustrated in FIGURE 8.Due to the method of making and the tapered thickness of the wall of thecatheter 2, the catheter 2 will retain its original shape withoutbuckling while the needle 3 is being with drawn. As a result, the end ofthe catheter 2 remains in the body cavity as the end of the needle 3 iswithdrawn.

When the needle 3 is withdrawn, the catheter 2 is sufiiciently flexibleto follow the contour of the part in which it has been inserted withoutcutting or otherwise damaging the surrounding tissue.

As stated above, the needle 3 and handle 5 constitute a mandrel forforming the shape of the inside of the catheter 2. Thus, the internaltaper 9 at the outer end of handle 5 provides a Luer-type fitting forattaching the needle 3 to a standard syringe for inserting the catheter2, and the thicker wall portion 12 of the catheter surrounding theconically tapered portion 6 of the handle 5 produces a similar taperedfitting into which a tapered plug 13 may be inserted after the needle 3has been withdrawn, see FIGURE 9, to connect the catheter to anextension tube 14. Fluids then may be supplied to or withdrawn throughthe catheter 2. When it is desired to intermittently use the catheter 2as, for example, to give intravenous feeding through the catheter 2 atintervals of time over a long period, the plug 13 with attachedextension tube 14 is used alternately with a rod type plug or stopper 15for preventing a reverse flow between periods of use.

The rod type plug 15 may be composed of a suitable plastic and coatedwith an anti-coagulant substance, such as heperin, to prevent blood fromclotting or from sticking to the plug. The plug 15 also may include arelatively large amount of a bactericide, such as organic compounds oftin and quaternary ammonium compounds, which are molded therein and havea bactericidal effect even when located at a distance from the organism.

In addition to providing a method of fabricating a catheter, the presentinvention provides a novel form of combined needle 3 and catheter 2. Asshown in FIGURES 1 and 5 to 8, inclusive, the catheter 2 has a beveledend 16 at least roughly parallel to the flat beveled end 4 of the needle3, and of an extremely smooth, thin and rounded contour 17 from theouter periphery of the needle shank 3 to the outer periphery of thecatheter 2. In addition, the catheter 2 has a wall of graduallyincreasing thickness from the rounded end 17 to its opposite end.Furthermore, the catheter 2 has a standard Luer fitting 12 of conicalshape formed as an integral part of the catheter and of greater wallthickness than the tube section. In addition, the catheter 2 has aclose, perfect fit on the outer periphery of the needle 3 because of themethod by which it is made.

It will now be observed that the present invention provides an improvedmethod of making a catheter directly on the needle with which it is usedto insert the catheter in a body cavity. It will also be observed thatthe present invention provides an improved needle and a catheter in aself-contained sterile unit which facilitates the insertion of the endof the catheter into a body cavity and the removal of the needletherefrom. It will still further be observed that the present inventionprovides an improved catheter and needle unit which is of relativelysimple and compact construction, adapted for economical manufacture andone which is reliable in operation for inserting the end of a plasticcatheter into a body cavity.

While alternate steps of a method and a single form of combined catheterand needle are herein described and illustrated, it will be understood,that the steps of the method and form of the resulting product may bechanged and modified within the scope of the present invention.

Therefore, without limitation in this respect, the invention is definedby the following claims.

I claim:

1. A surgical unit comprising a needle having a smooth continuous shankwith one end beveled to provide a sharp cutting edge and a handle at theother end, a catherer concentrically engaging the outer surface of theshank of the needle at the rear of the pointed end, said catheter havinga tubular wall and an end adjacent the pointed end of the needle thewall of said catheter closely fitting the shank of the needle at therear of the pointed end and substantially the entire length of thecatheter wall being of progressively increasing thickness from its endadjacent the pointed end of the needle toward the handle, and the end ofthe catheter adjacent the pointed end of the needle being thin andhaving rounded edges from the periphery of the needle to the peripheryof the catheter whereby to adapt the end of the catheter to follow thesharp pointed end of the needle into a body cavity and permit the needleto be withdrawn by relatively sliding the needle and catheter.

2. A surgical unit in accordance with claim 1 in which the catheterconcentrically engages the outer surface of the shank and handle of theneedle and is formed of a substantially integral one piece unit ofcoated resinous material.

3. A surgical unit in accordance with claim 1 in which the end of thecatheter is beveled at an angle roughly parallel to the beveled end ofthe needle.

4. A surgical unit in accordance with claim 1 in which the portion ofthe handle adjacent the needle is conical to provide a tapered fittingat the end of the catheter.

5. Surgical apparatus for delivering fluids to or withdrawing fluidsfrom the human body comprising, a penetrating element with a bevelpointed end and a shank projecting rearwardly therefrom and a hubcoupled with the rear of the shank, and an integral plastic cathetertube having a shank portion and hub portion integral therewithsurrounding the shank and hub, respectively, of the penetrating elementand having an end disposed in a plane at an angle to the axis of thepenetrating element and positioned adjacent the pointed end, saidcatheter tube having a tapered penetrating end positioned adjacent thepointed end of the penetrating element, said penetrating element andtube being cooperable to cause the tube to follow said pointed endthrough skin and tissue to locate the tapered end of the tube at thedesired position in the body, the tapered end of the catheter tube andthe pointed end of the penetrating element being relatively displaceableto permit the penetrating element to be Withdrawn through the cathetertube.

References Cited by the Examiner UNITED STATES PATENTS 3,017,884 1/62Doherty et a1.

3,055,361 9/62 Ballard.

3,064,651 11/62 Henderson 128221 3,082,769 3/63 Palmer 128-221 3,094,1246/63 Birtwell 128-348 3,097,646 7/63 Scislowicz.

OTHER REFERENCES Massa et al.: A Plastic Needle, Proc. Staff Meeting,Mayo Clinic, 25: 413-15, July 5, 1950.

RICHARD A. GAUDET, Primary Examiner.

1. A SURGICAL UNIT COMPRISING A NEEDLE HAVING A SMOOTH CONTINUOUS SHANKWITH ONE END BEVELED TO PROVIDE A SHARP CUTTING EDGE AND A HANDLE AT THEOTHER END, A CATHETER CONCENTRICALLY ENGAGING THE OUTER SURFACE OF THESHANK OF THE NEEDLE AT THE REAR OF THE POINTED END, SAID CATHETER HAVINGA TUBULAR WALL AND AN END ADJACENT THE POINT END OF THE NEEDLE THE WALLOF SAID CATHETER CLOSELY FITTING THE SHANK OF THE NEEDLE AT THE REAR OFTHE POINTED END AND SUBSTANTIALLY THE ENTIRE LENGTH OF THE CATHETER WALLBEING OF PROGRESSIVELY INCREASING THICKNESS FROM ITS END ADJACENT THEPOINTED END OF THE NEEDLE TOWARD THE HANDLE, AND THE END OF THE CATHETERADJACENT THE POINTED END OF THE NEEDLE BEING THIN AND HAVING ROUNDEDEDGES FROM THE PERIPHERY OF THE NEEDLE TO THE PERIPHERY OF THE CATHETERWHEREBY TO ADAPT THE END OF THE CATHETER TO FOLLOW THE SHARP POINTED ENDOF THE NEEDLE INTO A BODY CAVITY AND PERMIT THE NEEDLE TO BE WITHDRAWNBY RELATIVELY SLIDING THE NEEDLE AND CATHETER.